| Numerical simulation of chemically reacting flows continues to play an important role in the design and analysis of various industrial reactors. The comprehensive understanding and efficient design of rocket propulsion systems, high efficiency internal combustion engines, high altitude hypersonic vehicles, and many more require this technology. It is known that the chemical reactions in a reacting flow severely affect the overall physics of the flow itself. The strong coupling between the fluid flow and the chemistry, combined with the fundamental nonlinear nature of the phenomena, precludes obtaining a theoretically exact solution for reacting flows. Numerical analysis has become the preferred tool for extracting an understanding of these complex reacting flow problems.;Chemical reactions take place on extremely small time scales. Accordingly, chemically reacting flows are divided, for modeling purposes, into three general types: (1) Equilibrium; (2) Frozen; and (3) Finite rate. The first two of these are limiting cases which correspond to instantaneous reactions (equilibrium) and to no reactions (frozen). Most reacting flows occur on small but finite time scales. These finite rate chemically reacting flows are addressed here. The numerical methods used to compute the flow physics for these 'real' flows face a major difficulty. The difficulty is the stiffness of the mathematical models which are used to describe the transport characteristics of the different chemical species.;In addition, the numerical algorithm employed in the flow solver should be valid in the subsonic, transonic and supersonic flow regimes. It must also be stable (robust) and efficient. The purpose of this study is to develop a new numerical algorithm for chemically reacting flows applicable to both equilibrium and non-equilibrium chemical reactions. The non-iterative Pressure Implicit Splitting Operator (PISO) algorithm is chosen and used as a base-line flow solver. A new coupling procedure between flow solver and chemical reactions is developed which extends the basic PISO algorithm to reacting flows. The main objectives of this study are to: (1) Investigate the effects of equilibrium chemical reactions on fluid flows by comparing the calculated species concentrations and temperature of flow field with and without reactions; (2) Investigate the effects of finite rate reactions on fluid flows by comparing non-reacting, equilibrium, and finite rate reacting flows; (3) Develop a general coupling procedure between the flow field and the chemistry for predicting the physical properties of steady, unsteady, subsonic, and supersonic reacting flows.;The method developed in this dissertation employs multi-step reactions for the non-equilibrium problem. Detailed multi-species and multi-step models are used. Validation studies, including the calculation of the Burke-Schumann diffusion flame, the supersonic jet flame, the space shuttle main engine nozzle flow, the high pressure hypersonic wind tunnel flow, the hypersonic blunt body flow, the unsteady combustion chamber flow and the supersonic oblique detonation flow, show that the new procedure works well and effectively. |
